DAILY DIGEST

A Central Missouri State University team using more than 700 computers has found the largest prime number so far, a gargantuan 9,152,052-digit numeral.

The discovery, made Dec. 15 and confirmed Saturday, marked the second time this year that a cooperative computing project called the Great Internet Mersenne Prime Search has found a new largest prime. But like February's find, it falls short of the 10 million digit size required to earn a $100,000 prize from the Electronic Frontier Foundation.

The prime search project harnesses the collective power volunteered by more than 200,000 computers among which the task of scouring all possible Mersenne primes is divided. Although some prime numbers are used in encryption and other practical tasks, the largest primes are chiefly of academic interest.

A prime number is one that is evenly divisible only by itself and 1, and a Mersenne prime is a particular type that is 1 less than a power of 2. For example, 7 is a Mersenne prime because it's a prime number and is 2 to the third power minus 1.

Mersenne primes are named after Marin Mersenne, a French monk born in 1588 who investigated the numbers.

The prime discovered this month, the 43rd Mersenne prime found so far, is 2 to the power of 30,402,457 minus 1.